This invention relates generally to a machine for severing standing crops from the ground to initiate a harvesting process and, more particularly, to a rotary disc cutterbar having a preselected number of transversely oriented, rotatable discs having knives mounted thereon to sever standing crop by an impact action upon rotation of the discs.
Disc cutterbars have been utilized in agricultural harvesting implements for many years. Each disc cutterbar includes a plurality of transversely spaced disc cutters driven for rotation about a generally vertical axis. Each disc cutter has two or three knives pivotally mounted on the periphery thereof to sever standing crop from the ground through an impact action. For background information on the structure and operation of disc cutterbars, reference is made to U.S. Pat. No. 4,815,262, issued to E. E. Koch and F. F. Voler, the descriptive portions thereof being incorporated herein by reference.
The construction of disc cutterbars has evolved over the years to the configuration of having a modular construction with cutter modules and spacer modules, such as shown in U.S. Pat. No. 4,840,019, issued to L. J. Pingry, the descriptive portions of which are incorporated herein by reference. In some instances, the cutter modules and the spacer modules were integrally formed into one unit such as shown and described in U.S. Pat. No. 4,947,629, issued to R. Ermacora and H. Neuerburg.
It has been found that the specific use of the disc cutterbar apparatus, e.g. whether used as part of a disc mower, such as shown and depicted in U.S. Pat. No. 4,955,187, issued to C. van der Lely, which is typically supported at one end, or as part of a disc mower-conditioner which usually provides support to the cutterbar at both opposing ends thereof, carries with that particular use a different set of design parameters than other machines in which the cutterbar is utilized.
For example, the load imparted stresses relative to the spacer segments or modules on a disc mower cutterbar are different than the corresponding stresses on a disc mower-conditioner cutterbar. The tensile loads on the cutterbar are highest at the rear and center when used in a disc mower-conditioner, but at the front and inboard tractor end of the cutterbar when utilized in a disc mower.
A modular disc cutterbar of the type shown in the aforementioned Pingry patent is made up of segments comprising drive modules and spacer modules which can be joined at flange faces with retention mechanisms like threaded fasteners. The cutterbar spacer modules which are used to space and support the drive modules need to be sized to carry the highest loads. Because of the need to keep spacer modules with a uniform size and configuration no matter where the location the spacer is used along the transverse length of the cutterbar, the same spacer configuration is used along the full length of the cutterbar, resulting in some spacer modules being lightly loaded and constructed stronger and heavier than is structurally needed.
The weight of the completed disc mower assembly on a disc mower-conditioner needs to be as light as possible to minimize the required size of the cutterbar flotation springs and to reduce the inertia forces imposed on the cutterbar components when the cutterbar strikes and slides over an obstacle at high ground speeds. The weight of the cutterbar when utilized in a disc mower configuration also needs to be as light as possible to minimize the force and friction from the ground to minimize the wear of the ground contacting skid shoes, and also to minimize the damage to the crop which comes in contact with the skid shoes. A further consideration in keeping the weight of the cutterbar as light as possible is to reduce the loads imposed on the frame components when the disc mower is placed into a transport position in which the total weight of the cutterbar is supported by the frame. A corollary consideration is the desire to keep these frame components as light as possible.
When the disc cutterbar is used in a disc mower configuration, the cutterbar is provided with detachable skid shoes to ride across the ground and protect the structure of the cutterbar. In designing cutter and spacer modules to minimize weight of the cutterbar, means for mounting the skid shoes to the cutter modules must be provided. The mounting of the skid shoes must permit a convenient mounting and removal of the skid shoe from the cutter module, while allowing the cutter module to have adequate surface area for heat dissipation, to have easy access to the oil level check plug and to the oil drain plug, and to be designed with an ample reservoir for oil therein.
The design of a cutter module that is clamped between opposing spacer modules requires a means by which a rock guard can be mounted on the cutterbar forwardly of each cutter module to protect the cutter module from damage. The rock guard is cooperatively associated with the skid shoe to protect the cutter module from damage. Known rock guard designs are supported on a flange in front of the disc cutter and threaded fasteners are used to clamp the rock guard to the disc cutter unit. As a result, the supporting flange has to be strong enough to support the rock guard when contacting an obstacle, requiring that the flange either be made large enough or of higher strength material to perform this function.
The rapid rotation of the disc members on which the cutting knives are mounted effects a cutting action to crop material through shear impact of the cutting knife into the standing crop. The knives are pivotally mounted on the disc member and can retract from the normal outwardly extended position during rotation of the disc member when striking an obstacle, such as a fence post or the like. Some known disc member structures carry knife stops to prevent the cutting knife from being able to rotate 360 degrees about its pivotal connection and wedging against the cutterbar housing. The provision of these knife stops increases the mass of the disc member being rotatably driven and is undesirable, yet necessary to restrict the movement of the cutting knives. Placement of the knife stops on the disc member can cause the disc member to be rotationally unbalanced, particularly if the stop is constructed such that cut crop can build up on the stop.
The drive mechanism for powering the rotation of the individual disc cutters typically includes a plurality of intermeshed spur gears rotatably mounted within a casing to rotate adjacent disc members in opposite directions. Some drive mechanisms utilize a drive shaft that extends transversely through the cutterbar casing. Corresponding bevel gears transfer rotational power from the drive shaft to the individual disc members.
In the known disc cutterbar mechanisms, the utilization of lubricating oil within the cutterbar casing lubricates the drive components; however, whenever the cutterbar is operating under sloped conditions, the lubricating oil would flow to the low point of the casing. Furthermore, the failure of any one of the gears comprising part of the drive components within the casing typically resulted in a catastrophic failure of the entire drive mechanism, as gear teeth sheared off of one gear would cause the failure of another gear set, and so on until substantially all of the gears sets were damaged.
The bearings supporting the transverse drive shaft require adequate lubrication to maintain adequate life, as do the radial lip seals at each end of the drive shaft components housed within the cutter modules. With the given design of the improved modular disc cutterbar, proper re-circulation of the lubricating fluid within the sealed cutter module is needed to obtain proper lubrication of the bearings and seals.
Disc cutterbars are known for leaving streaks, or strips of uncut crop material, at the location between the disc members that are diverging due to the alternating direction of rotation of consecutive disc members. It is believed that one cause for this crop streaking is the movement of cut crop off the disc cutterbar forwardly into the standing crop. Previous attempts to move cut crop rearwardly have been expressed in the form of crop lifters mounted on the surface of the disc member, such as shown in U.S. Pat. No. 4,549,390, issued to K. W. McLean, and in U.S. Pat. No. 4,567,716, issued to S. J. Makofka, P. J. Ehrhart and K. W. McLean. While such crop lifters have been shown to significantly improve the flow of cut crop rearwardly, the lifter structure increase the weight of the disc member.